Core Security Components in Kubernetes

Core Security Components in Kubernetes

Understanding Kubernetes security requires familiarity with its core security components and how they interact. The API server serves as the central control point, authenticating users and authorizing actions based on Role-Based Access Control (RBAC) policies. Every interaction with the cluster passes through the API server, making it the primary enforcement point for security policies. Securing the API server through proper authentication, authorization, and admission control forms the foundation of cluster security.

Authentication in Kubernetes supports multiple methods, including client certificates, bearer tokens, and external identity providers. However, authentication only verifies identity; authorization determines what authenticated users can do. RBAC provides fine-grained permission control, allowing administrators to define roles with specific permissions and bind them to users or service accounts. Well-designed RBAC policies follow the principle of least privilege, granting only the minimum permissions necessary for each user or application.

Admission controllers add another layer of security by intercepting requests after authentication and authorization but before persistence to etcd. These controllers can validate, mutate, or reject requests based on custom policies. Pod Security Policies (now deprecated) and Pod Security Standards represent specific admission controllers focused on pod security. Understanding admission control enables organizations to implement policy-as-code approaches to security enforcement.